ANTIBIOTICS have ended untold human misery by curing bacterial infections, yet we are losing these wonder drugs. New Scientist has reported on the rise of antibiotic-resistant bacteria for years.

Missing Microbes is partly about that. But it is mainly a story you may not know, about the damage antibiotics do when they actually work. There have already been reports that antibiotics may cause obesity by disrupting gut bacteria that play a role in nutrition. Farmers use antibiotics to fatten livestock; we’re not so different, it seems. This book explains that such microbial disruption is widespread, often irreversible, and surprisingly damaging.

Antibiotics may also have made us taller. And by disrupting immune reactions, they may be involved in modern plagues such as diabetes, allergies, some cancers, maybe even autism.

Author Martin Blaser is a microbiologist at New York University’s School of Medicine and head of the Human Microbiome Program, an international project to use gene sequencing to identify microbes living in and on every human. So you might expect him to say that those bugs are responsible for a lot of our health, or the lack of it.

The great thing about this very readable account is that he tells us why he thinks so, enthusiastically describing how the research was done, what its limits are and what it means for us – right up to inquiries that are still under way.

It’s all frighteningly convincing. We evolved with loads of microbes, especially in our gut; our bacteria outnumber our own cells 10 to 1. These complex communities are the delicately balanced results of long evolutionary struggles. We disrupt them at our peril.

Yet every time we take a typical antibiotic, we carelessly wipe out masses of innocent bacterial bystanders. Experiments in mice and epidemiology in humans implicate these losses in autoimmune disorders such as asthma, type 1 diabetes and Crohn’s disease. Meanwhile, babies delivered by Caesarian section are not colonised by the right bacteria, from their mother’s birth canal. And gut microbes affect nerves and immunity in ways that have led researchers to investigate potential links to autism.

What we have overlooked in our cavalier treatment of our bacterial guests is their complexity. For example, I thought Helicobacter pylori was a proven bad guy, the cause of stomach ulcers. Yes, it causes inflammation, but it now seems that this triggers other events which protect us from oesophageal cancer. Who knew?

Blaser’s biggest worry is that by wiping out some microbes, we are leaving less-diverse microbial ecosystems that are more vulnerable to disruption, and losing helpful bacteria that protect us from nasty ones. We may need such allies against the next bacterial plague. We may no longer have them.

Our flimsy microbial diversity may stand little chance against the next bacterial plague

The remedy is to replace our kill-everything antibiotics with targeted treatments that kill only the bad bugs, and to create better diagnostics so we know what to target. Helpfully, we also need this to fight antibiotic resistance.

The World Health Organization says developing such treatments will require handling them like a public good, not a commercial game. Is this approach possible? Its cost, Blaser notes, may be less than we pay for our indiscriminate war on bacteria. Let’s hope the pharmaceutical industry and governments are listening.